iPhone HEIC photos: what metadata they carry and how to clean them without losing HDR
If you have an iPhone, your photos are almost certainly HEIC: it is the camera’s default format. They carry the same data as a JPEG — where, when and with which phone — plus some of Apple’s own. And they have a catch when you clean them: the brightness of HDR photos also depends on their metadata.
Why your photos are HEIC
The iPhone saves photos as HEIC because it takes less space than a JPEG of the same quality. It is changed in Settings → Camera → Formats: “High Efficiency” is HEIC and “Most Compatible” is JPEG.
When you move photos to a computer, the iPhone can convert them to JPEG on its own: it depends on Settings → Photos → “Transfer to Mac or PC”, which converts when set to “Automatic” and does not when set to “Keep Originals”. That is why you sometimes have the same photo in both formats without knowing.
What is inside
- Where you were: the GPS coordinates, the altitude and the direction the phone was pointing.
- Who you are: the exact iPhone model, the lens, the iOS version and, in Apple’s maker note, identifiers linking the photo to your photo library.
- When it happened: the date and time, with the time zone.
- The technical side: exposure, colour profile and, in HDR photos, the gain map that gives them their extra brightness on a compatible screen.
The HDR catch
iPhone HDR photos store a normal image and, separately, a gain map saying how much brighter each area should look. To apply it, Apple needs two pieces of data that live in the metadata: one in the XMP and two values in its maker note inside the EXIF.
A tool that deletes everything without telling them apart leaves the photo without its HDR: it still shows, but dull, like a normal photo. KillEXIF itself had that bug until we measured it with real photos.
How KillEXIF cleans them
KillEXIF cleans the HEIC without converting it: a HEIC goes in and a HEIC comes out, with the image identical, byte for byte. It removes the location, the model, the dates and the photo-library identifiers, and of Apple’s data it keeps only those two HDR values, with the reason in plain sight: “Makes the photo display in HDR”. We checked it with real HDR photos: the peak brightness of the clean photo is the same as the original’s, and neither the GPS nor the identifier is left in it.
On the website it is free and unlimited. In the Mac and Windows apps, HEIC is part of the paid version; what is free there is seeing what any photo carries.
If you only want to remove the location
The iPhone itself lets you share a photo without its location: when sharing, “Options” and turn off “Location”. It applies to that share and only removes the location: the model, the dates and the rest stay inside. If you want to remove everything else, or clean many photos at once, do it before sharing them.